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D. Courault

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Courault, D., Albert, I., Perelle, S., Fraisse, A., Renault, P., Salemkour, A., Amato, P. (2017). Assessment and risk modeling of airborne enteric viruses emitted from wastewater reused for irrigation. Science of the Total Environment (592), 512 - 526. DOI : 10.1016/j.scitotenv.2017.03.105

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Papers by D. Courault

Détection Supervisée Des Dates Des Opérations De Fauche Des Prairies

Soumis le 30 juin 2010 ; accepté le 28 juin 2011 -© Revue Télédétection, 2011, vol. 10, n os 2-3,... more Soumis le 30 juin 2010 ; accepté le 28 juin 2011 -© Revue Télédétection, 2011, vol. 10, n os 2-3, p. 129-136 Résumé : Nous présentons dans ce travail une méthode de détection de changements appliquée à une séquence d'images de télédétection à hautes résolutions spatiale et temporelle pour détecter certaines pratiques culturales comme la fauche et l'irrigation. La zone d'étude est la plaine de la Crau située au sud-est de la France. Les images utilisées sont issues du satellite Taïwanais FORMOSAT-2 à hautes résolutions spatiale (8m) et temporelle (potentiellement une image par jour). La méthode proposée est basée sur la combinaison d'une technique de mesure de différence (dissimilarité) et des contours actifs basés régions. La première permet la localisation des zones qui ont évolué entre deux dates d'acquisition successives d'images d'une même scène, tandis que la deuxième affine le résultat en segmentant l'image de différence en zones de changements ...

NPP VIIRS land surface temperature product validation using worldwide observation networks

2013 IEEE International Geoscience and Remote Sensing Symposium - IGARSS

Thermal infrared satellite observations of the Earth's surface are key components in estimating t... more Thermal infrared satellite observations of the Earth's surface are key components in estimating the surface skin temperature over global land areas. This work presents validation methodologies to estimate the quantitative uncertainty in Land Surface Temperature (LST) product derived from the Visible Infrared Imager Radiometer Suite (VIIRS) onboard Suomi National Polar-orbiting Partnership (NPP) using ground-based measurements currently made operationally at many field and weather stations around the world. Over heterogeneous surfaces in terms of surface types or biophysical properties (e.g., vegetation density, emissivity), the validation protocol accounts for land surface spatial variability around the ground station. Over sparse vegetation canopies, the methodology accounts for viewing directional effects and sun configuration when validating VIIRS LST products.

Evaluation of Nonparametric Machine-Learning Algorithms for an Optimal Crop Classification Using Big Data Reduction Strategy

Remote Sensing in Earth Systems Sciences

Quels sont les capteurs et les méthodes disponibles en télédétection pour aider à la gestion de l’eau ?

HAL (Le Centre pour la Communication Scientifique Directe), 2020

Albedo and LAI estimates from FORMOSAT-2 data for crop monitoring

Remote Sensing of Environment, 2009

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Airborne thermal data for evaluating the spatial distribution of actual evapotranspiration over a watershed in oceanic climatic conditions—application of semi-empirical models

International Journal of Remote Sensing, 1996

Page 1. INT. 1. REMOTE SENSING, 1996, VOL. 17, NO. 12, 2281-2302 Airborne thermal data for evalua... more

Combined use of FORMOSAT-2 images with a crop model for biomass and water monitoring of permanent grassland in Mediterranean region

Hydrology and Earth System Sciences, 2010

The aim of this study is to propose methods to improve crop and water management in Mediterranean... more The aim of this study is to propose methods to improve crop and water management in Mediterranean regions. At landscape scale, there is a spatial variability of agricultural practices, particularly for grasslands irrigated by flooding. These grasslands are harvested three times per year and produce high quality hay, but their productions decreased significantly during the last few years because of the water scarcity. It is therefore important to assess the real water requirement for crops in order to predict productions in the case of agricultural practice modifications. Until now, the spatial variability of agricultural practices was obtained through surveys from farmers, but this method was tedious to describe an entire region. Thus, the specific aim of the study is to develop and assess a new method based on a crop model for estimating water balance and crop yield constrained by products derived from optical remote sensing data with high spatio-temporal resolution. A methodology, based on the combined use of FORMOSAT-2 images and the STICS crop model, was developed to estimate production, evapotranspiration and drainage of irrigated grasslands in "the Crau" region in the South Eastern France. Numerous surveys and ground measurements were performed during an experiment conducted in 2006. Simple algorithms were developed to retrieve the dynamic of Leaf Area Index (LAI) for each plot and the main agricultural practices such as mowing and irrigation dates. These variables computed from remote sensing were then used to parameterize STICS, applied at region scale to estimate the spatial variability of water budget associated with the biomass productions. Results are displayed at the farm

Impact of local climate variability on crop model estimates in the south-east of France

Climate Research, 2001

Most crop models use climatic data recorded from weather stations located on standard surfaces su... more Most crop models use climatic data recorded from weather stations located on standard surfaces such as grass. These environmental conditions represent meso-climates typical of the region but often do not reflect the crop micro-climate. The aim of this paper is to show the effect of the environment surrounding the weather stations on the variability of climatic data and to estimate the impact of these variations on different outputs of crop models (crop cycle length, yield, irrigation and quantities of fertilizer). The crop model STICS was used with different management strategies. Simulations were performed using climatic data measured at 5 meteorological stations surrounded by different environments (wet grassland, dry area, wheat, soybean and irrigated wheat) in a small agricultural region in the southeast of France. The distances between the stations ranged from 3 km to a maximum of 10 km. The region is flat and has 1 weather station of the conventional national synoptic network. The measurements show that, even at such a small regional scale, the spatial variability due to the environment surrounding a weather station is important and should be taken into account. Significant discrepancies were observed both for yield and irrigation, as well as crop cycle length, according to the climatic data considered. Differences in soil moisture produce the greatest differences in air temperature between the weather stations and, consequently, the greatest discrepancies between the outputs of the crop models.

Estimation of surface fluxes in a small agricultural area using the three-dimensional atmospheric model Meso-NH and remote sensing data

Canadian Journal of Remote Sensing, 2003

To provide an accurate water budget over a whole basin, hydrological models need to know the spat... more To provide an accurate water budget over a whole basin, hydrological models need to know the spatial variability of evapotranspiration at the watershed scale. The three-dimensional (3D) atmospheric models can provide such estimations at a regional scale, since they calculate the different energy and water fluxes by accounting for the landscape heterogeneity with a mesh grid varying from a few metres to several kilometres. We have used such a transfer model (Meso-NH) at a high spatial scale (50 m) to simulate the small agricultural region of the Alpilles (4 km ~ 5 km), where an experiment took place in 1997 and included intense ground measurements on different types of crops and airborne and satellite data collection. It was the first time that this model was used at such a fine resolution. The aim of this paper is to analyze the effects of the various crops on the spatial variability of the main energy fluxes, particularly evapotranspiration. We also wished to validate Meso-NH from this important available dataset. All input parameters were derived from remote sensing or airborne data: leaf area index (LAI) and albedo were computed from polarization and directionality of the earth's reflectances (POLDER) images. Roughness length was estimated combining both a land-use map obtained from Satellite pour l'Observation de la Terre (SPOT) images and the POLDER images. Maps of the main energy fluxes and temperatures were simulated for two periods in April and June and showed large spatial variations because of differences in soil moisture and in roughness of the crop types. Comparisons between the simulations and the measurements gave satisfactory results. Thermal images acquired by the infrared airborne camera were in good agreement with the surface temperatures estimated by the model. Significant differences were observed when we compared, on the same area, the value of averaged fluxes with the value of fluxes calculated with averaged surface parameters. This was due to the nonlinearity processes associated with averaging of environmental variables. The interest in using a mesoscale model applied at microscale is that coherent structures can be observed in the surface boundary layer, particularly on transects of the vertical wind speed. Such structures cannot be simulated at a larger scale or analyzed with simplified models. Remote sensing data acquired at a fine spatial resolution are a useful tool to provide accurate surface parameters to such a model. This allows quantification of the effect of each crop type on the spatial variation of temperature and evapotranspiration and thus improves our knowledge of the water budget of an agricultural landscape and the watershed functioning. nécessaires afin d'approfondir l'étude de ces structures et analyser les problèmes liés aux changements d'échelle. Néanmoins, il ressort que les données de télédétection acquises à haute résolution apportent des informations utiles à de tels modèles en leur permettant d'accéder à une caractérisation plus fine de la surface améliorant ainsi l'estimation des flux transmis à l'atmosphère.

MUREX: a land-surface field experiment to study the annual cycle of the energy and water budgets

Annales Geophysicae, 1999

The MUREX (monitoring the usable soil reservoir experimentally) experiment was designed to provid... more The MUREX (monitoring the usable soil reservoir experimentally) experiment was designed to provide continuous time series of ®eld data over a long period, in order to improve and validate the Soilvegetation-Atmosphere Transfer (SVAT) parameterisations employed in meteorological models. Intensive measurements were performed for more than three years over fallow farmland in southwestern France. To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterised, and surface water and energy¯uxes, vegetation biomass, soil moisture pro®les, surface soil moisture and surface and soil temperature were monitored. Additional physiological measurements were carried out during selected periods to describe the biological control of the¯uxes.

Integrating soil and water resources in local development framework: the ASTUCE & TIC program

Urban growth is a factor of productivity but urban spreading is a major threat for soil and water... more Urban growth is a factor of productivity but urban spreading is a major threat for soil and water resources. Local development must consider a city with its hinterland (Figures 1 and 2). Soil and water resources are needed for food production, water supply and their degradation can impair the possibilities of cities to generate wealth and the economic resources for financing local development and managing public resources (Figure 3). Data are generally available but dispersed. There exist already numerous models, separately ...

Mapping surface sensible heat flux from thermal infrared and reflectances data using various models over the Alpilles test site

First International Symposium on Recent Advances in Quantitative Remote Sensing, 2002

ABSTRACT: Maps of surface sensible heat flux were generated from remote sensing images over the A... more ABSTRACT: Maps of surface sensible heat flux were generated from remote sensing images over the Alpilles test site in the South of France using various models: a direct flux equation using surface temperature, air temperature, wind speed and surface roughness: the SEBAL model (Bastiaanssen el a/. I998a) which computed the wind speed and the air temperature by using the spatial variation of albedo and surface temperature; a microscale aggregation model (Hasager and Jensen 1999) which consists in a linearized version of the ...

Monitoring energy and mass transfers during the Alpilles-ReSeDA experiment

Agronomie, 2002

The Alpilles-ReSeDA program was initiated to develop and test methods for interpreting remote sen... more The Alpilles-ReSeDA program was initiated to develop and test methods for interpreting remote sensing data that could lead to a better evaluation of soil and vegetation processes. This article presents the experiment that was setup in order to acquire the necessary data to achieve this goal. Intensive measurements were performed for almost one year over a small agricultural region in the South of France (20 kilometers square). To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterized, and surface energy fluxes, vegetation biomass, vegetation structure, soil moisture profiles, surface soil moisture, surface temperature and soil temperature were monitored. Additional plant physiological measurements and a full characterization of physical soil parameters were also carried out. After presenting the different types of measurements, examples are given in order to illustrate the variability of soils and plant processes in the area in response to the experienced climate. surface energy fluxes / evapotranspiration / soil moisture / soil physical properties / experiment / vegetation characterization Résumé-Suivi des échanges d'énergie et de masse au cours de l'expérimentation Alpilles-ReSeDA. Le programme Alpilles-ReSeDA a été mis en place pour développer et tester des méthodes permettant une meilleure utilisation des données de télédétection pour le suivi du fonctionnement des sols et des cultures. Cet article présente l'expérimentation qui a été réalisée pour acquérir un jeu de données permettant cette analyse. Des mesures intensives ont été réalisées pendant presque une année sur une petite région agricole du Sud de la France (20 kilomètres carrés). De façon à suivre l'ensemble des processus contrôlant les échanges surface-atmosphère, l'ensemble des paramètres climatiques locaux ont été mesurés, ainsi que les flux d'énergie de surface, les caractéristiques de structure de la végétation et du sol, l'humidité et les températures du sol, la température de surface. Des mesures des paramètres physiologiques des plantes et des caractéristiques physiques des sols ont également été entreprises. Après avoir présenté les différents types de mesures réalisées, des exemples présentant la variabilité des couverts végétaux et des sols dans la zone d'étude sont présentés.

Analyse des sécheresses de 1988 à 1990 en France à partir de l'analyse combinée de données satellitaires NOAA-AVHRR et d'un modèle agrométéorologique

Agronomie, 1994

Analyse des sécheresses de 1988 à 1990 en France à partir de l'analyse combinée de données satell... more Analyse des sécheresses de 1988 à 1990 en France à partir de l'analyse combinée de données satellitaires NOAA-AVHRR et d'un modèle agrométéorologique D Courault* P Clastre JP Guinot, B Seguin INRA, station de bioclimatologie, centre d'Avignon, BP91, F84143 Montfavet, France (Reçu le 20 décembre 1992; accepté le 2 décembre 1993) Résumé-Les satellites météorologiques ont été largement utilisés ces dernières années pour le suivi de la végétation, principalement en utilisant l'indice de végétation. Les données thermiques apportent une information complémentaire sur les conditions hydriques des cultures. La température de surface est en effet reliée indirectement à l'évapotranspiration. L'objectif de cette étude est de proposer une méthodologie opérationnelle pour estimer l'évapotranspiration à large échelle, en utilisant de façon combinée des images AVHRR composites de 5j des satellites NOAA et un modèle agrométéorologique Magret. La relation simplifiée basée sur le bilan d'énergie, qui relie de façon linéaire l'évaporation au rayonnement net et à la différence entre la température de surface et celle de l'air, a été utilisée. Les températures de surface sont déduites des mesures satellitaires à l'aide d'une méthode multispectrale ("split-window") qui a été améliorée pour application aux couverts végétaux. La méthode proposée a été appliquée à l'échelle de la France afin de détecter les effets des sécheresses de 1988 à 1990. Il est démontré que les différences de températures entre la surface et l'air, cumulées dans le temps sont significatives des stress hydriques subis par les cultures et permettent de distinguer les variations climatiques régionales. L'analyse des cartes d'évaporation permet une évaluation globale des sécheresses en France au cours des dernières années. température de surface / NOAA / évapotranspiration / modèle agrométéorologique Summary-Analysis of droughts in France from 1988 to 1990 using NOAA-AVHRR data and an agrometeorological model. The study reported here aimed at proposing an operational methodology to estimate actual evaporation on a large scale, using AVHRR images of the NOAA satellite and an agrometeorological model. The method was applied to detect drought effects for 3 yr (1988-1989-1990) over all of France. For each year, 48 cloud-free images were selected on a 5-d basis. Surface temperatures obtained from AVHRR images were combined with the output data of an agrometeorological model using ground data from 20 stations. The simplified relationship, based on an energy budget relating midday surface-air temperature difference to daily evaporation and net radiation was used for this study. A new local splitwindow method was applied to the images in order to get a better accuracy of surface temperature. Analysis of the cumulative surface-air temperature difference revealed a regional climatic effect. Evaporation maps provided a global evaluation of droughts in all of France for the 3 yr studied. surface temperature / NOAA / evaporation / agrometeoralogical model / regional scale *Correspondance et tirés à part. régions. La cause principale en est la faible pluviométrie. Les cartes des écarts à la normale des hauteurs de précipitations données par Météo-France mettent en évidence l'évolution de la sécheresse de 1988 à 1990. En 1988, elle ne concernait que la région sud-est; en 1989, elle a touché l'ensemble de la

Evaporation for maritime catchment combining a meteorological model with vegetation information and airborne surface temperatures

Agricultural and Forest Meteorology, 1996

Estimation of daily fluxes at regional scale using thermal infrared data through semi-empirical m... more Estimation of daily fluxes at regional scale using thermal infrared data through semi-empirical models is problematic under oceanic climates, due to the frequency of cloudy days and the subsequent low availability of thermal infrared images (TR). The gap between available satellite information must therefore be bridged by simulation from cropwater balance models. In an experiment on a small agricultural catchment in Brittany (NW France) we have used TIR data and an agrometeorological model to estimate actual evapotranspiration (AET). The model is described: a new module has been added to take into account the canopy development through the LA1 variations. Continuous micrometeorological measurements were made on three characteristic surfaces (meadow, wheat and stubble field). The agrometeorological model simulated correctly the main energy fluxes and the surface temperatures for these changing climatic conditions. Thermal images covering the whole catchment were acquired on 6 August 1993 using an airborne infrared camera. The comparison between the surface temperatures acquired by the camera and the ground measurements was satisfactory. We discussed the possibilities of combining these data with the model to estimate AET at the catchment scale.

Influence of agricultural practices on micrometerological spatial variations at local and regional scales

International Journal of Remote Sensing, 2009

Modélisation des transferts de masse et d'énergie dans le continuum sol-plante-atmosphère sur sol cultivé: expérience Alpilles

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more

Validation of MODIS albedo products with higher spatial resolution estimates from FORMOSAT-2

International audienc

Uncertainties on Evapotranspiration Derived from Landsat Depending on Realibility of Albedo Input Data over a Mediterranean Agricultural Regiion

International audienc

Surface temperature and evapotranspiration: Application of local scale methods to regional scales using satellite data

Remote Sensing of Environment, 1994

Remotely sensed surface temperatures have proven useful for monitoring evapotranspiration (ET) ra... more

Détection Supervisée Des Dates Des Opérations De Fauche Des Prairies

Soumis le 30 juin 2010 ; accepté le 28 juin 2011 -© Revue Télédétection, 2011, vol. 10, n os 2-3,... more Soumis le 30 juin 2010 ; accepté le 28 juin 2011 -© Revue Télédétection, 2011, vol. 10, n os 2-3, p. 129-136 Résumé : Nous présentons dans ce travail une méthode de détection de changements appliquée à une séquence d'images de télédétection à hautes résolutions spatiale et temporelle pour détecter certaines pratiques culturales comme la fauche et l'irrigation. La zone d'étude est la plaine de la Crau située au sud-est de la France. Les images utilisées sont issues du satellite Taïwanais FORMOSAT-2 à hautes résolutions spatiale (8m) et temporelle (potentiellement une image par jour). La méthode proposée est basée sur la combinaison d'une technique de mesure de différence (dissimilarité) et des contours actifs basés régions. La première permet la localisation des zones qui ont évolué entre deux dates d'acquisition successives d'images d'une même scène, tandis que la deuxième affine le résultat en segmentant l'image de différence en zones de changements ...

NPP VIIRS land surface temperature product validation using worldwide observation networks

2013 IEEE International Geoscience and Remote Sensing Symposium - IGARSS

Thermal infrared satellite observations of the Earth's surface are key components in estimating t... more Thermal infrared satellite observations of the Earth's surface are key components in estimating the surface skin temperature over global land areas. This work presents validation methodologies to estimate the quantitative uncertainty in Land Surface Temperature (LST) product derived from the Visible Infrared Imager Radiometer Suite (VIIRS) onboard Suomi National Polar-orbiting Partnership (NPP) using ground-based measurements currently made operationally at many field and weather stations around the world. Over heterogeneous surfaces in terms of surface types or biophysical properties (e.g., vegetation density, emissivity), the validation protocol accounts for land surface spatial variability around the ground station. Over sparse vegetation canopies, the methodology accounts for viewing directional effects and sun configuration when validating VIIRS LST products.

Evaluation of Nonparametric Machine-Learning Algorithms for an Optimal Crop Classification Using Big Data Reduction Strategy

Remote Sensing in Earth Systems Sciences

Quels sont les capteurs et les méthodes disponibles en télédétection pour aider à la gestion de l’eau ?

HAL (Le Centre pour la Communication Scientifique Directe), 2020

Albedo and LAI estimates from FORMOSAT-2 data for crop monitoring

Remote Sensing of Environment, 2009

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Airborne thermal data for evaluating the spatial distribution of actual evapotranspiration over a watershed in oceanic climatic conditions—application of semi-empirical models

International Journal of Remote Sensing, 1996

Page 1. INT. 1. REMOTE SENSING, 1996, VOL. 17, NO. 12, 2281-2302 Airborne thermal data for evalua... more

Combined use of FORMOSAT-2 images with a crop model for biomass and water monitoring of permanent grassland in Mediterranean region

Hydrology and Earth System Sciences, 2010

The aim of this study is to propose methods to improve crop and water management in Mediterranean... more The aim of this study is to propose methods to improve crop and water management in Mediterranean regions. At landscape scale, there is a spatial variability of agricultural practices, particularly for grasslands irrigated by flooding. These grasslands are harvested three times per year and produce high quality hay, but their productions decreased significantly during the last few years because of the water scarcity. It is therefore important to assess the real water requirement for crops in order to predict productions in the case of agricultural practice modifications. Until now, the spatial variability of agricultural practices was obtained through surveys from farmers, but this method was tedious to describe an entire region. Thus, the specific aim of the study is to develop and assess a new method based on a crop model for estimating water balance and crop yield constrained by products derived from optical remote sensing data with high spatio-temporal resolution. A methodology, based on the combined use of FORMOSAT-2 images and the STICS crop model, was developed to estimate production, evapotranspiration and drainage of irrigated grasslands in "the Crau" region in the South Eastern France. Numerous surveys and ground measurements were performed during an experiment conducted in 2006. Simple algorithms were developed to retrieve the dynamic of Leaf Area Index (LAI) for each plot and the main agricultural practices such as mowing and irrigation dates. These variables computed from remote sensing were then used to parameterize STICS, applied at region scale to estimate the spatial variability of water budget associated with the biomass productions. Results are displayed at the farm

Impact of local climate variability on crop model estimates in the south-east of France

Climate Research, 2001

Most crop models use climatic data recorded from weather stations located on standard surfaces su... more Most crop models use climatic data recorded from weather stations located on standard surfaces such as grass. These environmental conditions represent meso-climates typical of the region but often do not reflect the crop micro-climate. The aim of this paper is to show the effect of the environment surrounding the weather stations on the variability of climatic data and to estimate the impact of these variations on different outputs of crop models (crop cycle length, yield, irrigation and quantities of fertilizer). The crop model STICS was used with different management strategies. Simulations were performed using climatic data measured at 5 meteorological stations surrounded by different environments (wet grassland, dry area, wheat, soybean and irrigated wheat) in a small agricultural region in the southeast of France. The distances between the stations ranged from 3 km to a maximum of 10 km. The region is flat and has 1 weather station of the conventional national synoptic network. The measurements show that, even at such a small regional scale, the spatial variability due to the environment surrounding a weather station is important and should be taken into account. Significant discrepancies were observed both for yield and irrigation, as well as crop cycle length, according to the climatic data considered. Differences in soil moisture produce the greatest differences in air temperature between the weather stations and, consequently, the greatest discrepancies between the outputs of the crop models.

Estimation of surface fluxes in a small agricultural area using the three-dimensional atmospheric model Meso-NH and remote sensing data

Canadian Journal of Remote Sensing, 2003

To provide an accurate water budget over a whole basin, hydrological models need to know the spat... more To provide an accurate water budget over a whole basin, hydrological models need to know the spatial variability of evapotranspiration at the watershed scale. The three-dimensional (3D) atmospheric models can provide such estimations at a regional scale, since they calculate the different energy and water fluxes by accounting for the landscape heterogeneity with a mesh grid varying from a few metres to several kilometres. We have used such a transfer model (Meso-NH) at a high spatial scale (50 m) to simulate the small agricultural region of the Alpilles (4 km ~ 5 km), where an experiment took place in 1997 and included intense ground measurements on different types of crops and airborne and satellite data collection. It was the first time that this model was used at such a fine resolution. The aim of this paper is to analyze the effects of the various crops on the spatial variability of the main energy fluxes, particularly evapotranspiration. We also wished to validate Meso-NH from this important available dataset. All input parameters were derived from remote sensing or airborne data: leaf area index (LAI) and albedo were computed from polarization and directionality of the earth's reflectances (POLDER) images. Roughness length was estimated combining both a land-use map obtained from Satellite pour l'Observation de la Terre (SPOT) images and the POLDER images. Maps of the main energy fluxes and temperatures were simulated for two periods in April and June and showed large spatial variations because of differences in soil moisture and in roughness of the crop types. Comparisons between the simulations and the measurements gave satisfactory results. Thermal images acquired by the infrared airborne camera were in good agreement with the surface temperatures estimated by the model. Significant differences were observed when we compared, on the same area, the value of averaged fluxes with the value of fluxes calculated with averaged surface parameters. This was due to the nonlinearity processes associated with averaging of environmental variables. The interest in using a mesoscale model applied at microscale is that coherent structures can be observed in the surface boundary layer, particularly on transects of the vertical wind speed. Such structures cannot be simulated at a larger scale or analyzed with simplified models. Remote sensing data acquired at a fine spatial resolution are a useful tool to provide accurate surface parameters to such a model. This allows quantification of the effect of each crop type on the spatial variation of temperature and evapotranspiration and thus improves our knowledge of the water budget of an agricultural landscape and the watershed functioning. nécessaires afin d'approfondir l'étude de ces structures et analyser les problèmes liés aux changements d'échelle. Néanmoins, il ressort que les données de télédétection acquises à haute résolution apportent des informations utiles à de tels modèles en leur permettant d'accéder à une caractérisation plus fine de la surface améliorant ainsi l'estimation des flux transmis à l'atmosphère.

MUREX: a land-surface field experiment to study the annual cycle of the energy and water budgets

Annales Geophysicae, 1999

The MUREX (monitoring the usable soil reservoir experimentally) experiment was designed to provid... more The MUREX (monitoring the usable soil reservoir experimentally) experiment was designed to provide continuous time series of ®eld data over a long period, in order to improve and validate the Soilvegetation-Atmosphere Transfer (SVAT) parameterisations employed in meteorological models. Intensive measurements were performed for more than three years over fallow farmland in southwestern France. To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterised, and surface water and energy¯uxes, vegetation biomass, soil moisture pro®les, surface soil moisture and surface and soil temperature were monitored. Additional physiological measurements were carried out during selected periods to describe the biological control of the¯uxes.

Integrating soil and water resources in local development framework: the ASTUCE & TIC program

Urban growth is a factor of productivity but urban spreading is a major threat for soil and water... more Urban growth is a factor of productivity but urban spreading is a major threat for soil and water resources. Local development must consider a city with its hinterland (Figures 1 and 2). Soil and water resources are needed for food production, water supply and their degradation can impair the possibilities of cities to generate wealth and the economic resources for financing local development and managing public resources (Figure 3). Data are generally available but dispersed. There exist already numerous models, separately ...

Mapping surface sensible heat flux from thermal infrared and reflectances data using various models over the Alpilles test site

First International Symposium on Recent Advances in Quantitative Remote Sensing, 2002

ABSTRACT: Maps of surface sensible heat flux were generated from remote sensing images over the A... more ABSTRACT: Maps of surface sensible heat flux were generated from remote sensing images over the Alpilles test site in the South of France using various models: a direct flux equation using surface temperature, air temperature, wind speed and surface roughness: the SEBAL model (Bastiaanssen el a/. I998a) which computed the wind speed and the air temperature by using the spatial variation of albedo and surface temperature; a microscale aggregation model (Hasager and Jensen 1999) which consists in a linearized version of the ...

Monitoring energy and mass transfers during the Alpilles-ReSeDA experiment

Agronomie, 2002

The Alpilles-ReSeDA program was initiated to develop and test methods for interpreting remote sen... more The Alpilles-ReSeDA program was initiated to develop and test methods for interpreting remote sensing data that could lead to a better evaluation of soil and vegetation processes. This article presents the experiment that was setup in order to acquire the necessary data to achieve this goal. Intensive measurements were performed for almost one year over a small agricultural region in the South of France (20 kilometers square). To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterized, and surface energy fluxes, vegetation biomass, vegetation structure, soil moisture profiles, surface soil moisture, surface temperature and soil temperature were monitored. Additional plant physiological measurements and a full characterization of physical soil parameters were also carried out. After presenting the different types of measurements, examples are given in order to illustrate the variability of soils and plant processes in the area in response to the experienced climate. surface energy fluxes / evapotranspiration / soil moisture / soil physical properties / experiment / vegetation characterization Résumé-Suivi des échanges d'énergie et de masse au cours de l'expérimentation Alpilles-ReSeDA. Le programme Alpilles-ReSeDA a été mis en place pour développer et tester des méthodes permettant une meilleure utilisation des données de télédétection pour le suivi du fonctionnement des sols et des cultures. Cet article présente l'expérimentation qui a été réalisée pour acquérir un jeu de données permettant cette analyse. Des mesures intensives ont été réalisées pendant presque une année sur une petite région agricole du Sud de la France (20 kilomètres carrés). De façon à suivre l'ensemble des processus contrôlant les échanges surface-atmosphère, l'ensemble des paramètres climatiques locaux ont été mesurés, ainsi que les flux d'énergie de surface, les caractéristiques de structure de la végétation et du sol, l'humidité et les températures du sol, la température de surface. Des mesures des paramètres physiologiques des plantes et des caractéristiques physiques des sols ont également été entreprises. Après avoir présenté les différents types de mesures réalisées, des exemples présentant la variabilité des couverts végétaux et des sols dans la zone d'étude sont présentés.

Analyse des sécheresses de 1988 à 1990 en France à partir de l'analyse combinée de données satellitaires NOAA-AVHRR et d'un modèle agrométéorologique

Agronomie, 1994

Analyse des sécheresses de 1988 à 1990 en France à partir de l'analyse combinée de données satell... more Analyse des sécheresses de 1988 à 1990 en France à partir de l'analyse combinée de données satellitaires NOAA-AVHRR et d'un modèle agrométéorologique D Courault* P Clastre JP Guinot, B Seguin INRA, station de bioclimatologie, centre d'Avignon, BP91, F84143 Montfavet, France (Reçu le 20 décembre 1992; accepté le 2 décembre 1993) Résumé-Les satellites météorologiques ont été largement utilisés ces dernières années pour le suivi de la végétation, principalement en utilisant l'indice de végétation. Les données thermiques apportent une information complémentaire sur les conditions hydriques des cultures. La température de surface est en effet reliée indirectement à l'évapotranspiration. L'objectif de cette étude est de proposer une méthodologie opérationnelle pour estimer l'évapotranspiration à large échelle, en utilisant de façon combinée des images AVHRR composites de 5j des satellites NOAA et un modèle agrométéorologique Magret. La relation simplifiée basée sur le bilan d'énergie, qui relie de façon linéaire l'évaporation au rayonnement net et à la différence entre la température de surface et celle de l'air, a été utilisée. Les températures de surface sont déduites des mesures satellitaires à l'aide d'une méthode multispectrale ("split-window") qui a été améliorée pour application aux couverts végétaux. La méthode proposée a été appliquée à l'échelle de la France afin de détecter les effets des sécheresses de 1988 à 1990. Il est démontré que les différences de températures entre la surface et l'air, cumulées dans le temps sont significatives des stress hydriques subis par les cultures et permettent de distinguer les variations climatiques régionales. L'analyse des cartes d'évaporation permet une évaluation globale des sécheresses en France au cours des dernières années. température de surface / NOAA / évapotranspiration / modèle agrométéorologique Summary-Analysis of droughts in France from 1988 to 1990 using NOAA-AVHRR data and an agrometeorological model. The study reported here aimed at proposing an operational methodology to estimate actual evaporation on a large scale, using AVHRR images of the NOAA satellite and an agrometeorological model. The method was applied to detect drought effects for 3 yr (1988-1989-1990) over all of France. For each year, 48 cloud-free images were selected on a 5-d basis. Surface temperatures obtained from AVHRR images were combined with the output data of an agrometeorological model using ground data from 20 stations. The simplified relationship, based on an energy budget relating midday surface-air temperature difference to daily evaporation and net radiation was used for this study. A new local splitwindow method was applied to the images in order to get a better accuracy of surface temperature. Analysis of the cumulative surface-air temperature difference revealed a regional climatic effect. Evaporation maps provided a global evaluation of droughts in all of France for the 3 yr studied. surface temperature / NOAA / evaporation / agrometeoralogical model / regional scale *Correspondance et tirés à part. régions. La cause principale en est la faible pluviométrie. Les cartes des écarts à la normale des hauteurs de précipitations données par Météo-France mettent en évidence l'évolution de la sécheresse de 1988 à 1990. En 1988, elle ne concernait que la région sud-est; en 1989, elle a touché l'ensemble de la

Evaporation for maritime catchment combining a meteorological model with vegetation information and airborne surface temperatures

Agricultural and Forest Meteorology, 1996

Estimation of daily fluxes at regional scale using thermal infrared data through semi-empirical m... more Estimation of daily fluxes at regional scale using thermal infrared data through semi-empirical models is problematic under oceanic climates, due to the frequency of cloudy days and the subsequent low availability of thermal infrared images (TR). The gap between available satellite information must therefore be bridged by simulation from cropwater balance models. In an experiment on a small agricultural catchment in Brittany (NW France) we have used TIR data and an agrometeorological model to estimate actual evapotranspiration (AET). The model is described: a new module has been added to take into account the canopy development through the LA1 variations. Continuous micrometeorological measurements were made on three characteristic surfaces (meadow, wheat and stubble field). The agrometeorological model simulated correctly the main energy fluxes and the surface temperatures for these changing climatic conditions. Thermal images covering the whole catchment were acquired on 6 August 1993 using an airborne infrared camera. The comparison between the surface temperatures acquired by the camera and the ground measurements was satisfactory. We discussed the possibilities of combining these data with the model to estimate AET at the catchment scale.

Influence of agricultural practices on micrometerological spatial variations at local and regional scales

International Journal of Remote Sensing, 2009

Modélisation des transferts de masse et d'énergie dans le continuum sol-plante-atmosphère sur sol cultivé: expérience Alpilles

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more

Validation of MODIS albedo products with higher spatial resolution estimates from FORMOSAT-2

International audienc

Uncertainties on Evapotranspiration Derived from Landsat Depending on Realibility of Albedo Input Data over a Mediterranean Agricultural Regiion

International audienc

Surface temperature and evapotranspiration: Application of local scale methods to regional scales using satellite data

Remote Sensing of Environment, 1994

Remotely sensed surface temperatures have proven useful for monitoring evapotranspiration (ET) ra... more